Raman spectroscopy is a label-free technique desired for molecular detection and molecular dynamics studies. Surface enhanced Raman scattering (SERS) improves the sensitivity by amplifying the original Raman scattering intensity for several or even tens of orders of magnitude. Spherical gold and silver nanoparticles have been used as substrates in SERS-based molecule detections due to their advantages in local scattering field enhancing, surface chemical modifications, biocompatibility, and well-established chemical synthesis processes. The intrinsic plasmon resonance of single nanoparticles and the plasmon coupling between adjacent nanoparticles are conditions for local field enhancing. The optimal SERS substrate of nanoparticle assemblies depends on the size, the local dielectric environment and the interparticle distance. SERS spectroscopy shows chemical-bond information, and is a useful method for label-free biomolecular imaging.
Nanoparticles are useful, in part, because of their unique, highly desirable properties that makes a superior detection platform for life science research, in vitro diagnostic testing, and in vivo imaging. One such property of nanoparticles is the increased intensity of Raman scattering which they contribute to the measurement of analyte species by Raman spectroscopy. The increased intensity results from the high density of SERS-active sites the nanoparticles contribute to the system. Other structures such as nanotips and nanorings have also been demonstrated for use in high resolution SERS spectroscopy and imaging. These structures provide significant field enhancement in experiments and in simulations.
Microfluidics is a field of work that deals with the fluid-based transport of mass, momentum, or energy. Microfluidic channels are completely enclosed and not in direct communication with the surrounding atmosphere.